In Boruto: Naruto Next Generations Episode 79, we finally got to see Mitsuki reunite with Boruto and Sarada. However, it seems like what happened it not what we are expecting.
In this episode, we see how Shikadai, Inojin, and Chocho fight Kokuyou and let Boruto and Sarada continue their chase on Mitsuki. However, team 10 was overpowered by Kokuyou and escaped.
Meanwhile, Boruto and Sarada faced Sekiei. The three of them fight, but when Sekiei is about to lose, Mitsuki came and helped Sekiei. Later on, Mitsuki attacked Boruto that causes him to lose his consciousness. With Mitsuki striking Boruto, does it mean he really betrayed his friends and the Hidden Leaf Village?
I think Mitsuki just did what he believes is right in that situation. Back in the previous arc, Orochimaru is allowing Mitsuki to choose his path. Mitsuki keeps on telling that Boruto is his sun and he is the moon, and there’s no way for a moon to shine if there’s no sun.
With the research that Orochimaru has been doing for all of his life, I can’t help but think that he has the intel about the impending threat in the future. It could be one of the reasons why he kept testing Mitsuki to choose on his own. If Orochimaru got the intel, he probably already told Mitsuki about it.
Since Mitsuki thinks that Boruto is his sun, he will be using himself to help Boruto reach his full potential. One way to do this is by infiltrating the enemy. Maybe Mitsuki wants to see exactly how big of a threat their opponent poses to the Hidden Leaf.
Similar to what Itachi did in the past, he sacrificed his whole clan to protect the Hidden Leaf for future threats. Itachi made himself as a traitor so he can spy to the enemies.
For Mitsuki’s case, he pretends to betray his friends and the Hidden Leaf like what Itachi did. By helping Sekiei and attacking Boruto in front of everyone, he wants Kokuyou to trust him so he can infiltrate the enemy quickly. Alternatively, he only did it to protect his friends knowing the fact that Kokuyou will surely outpower them.